Fig. 2 to 5 exhibit the resulting optical density of the HEBS-glass after exposure with a flood electron beam exposure system using a 29 kv, 25 kv, 20 kv and a 15 kv electron beam respectively at a number of dosage levels. The flood e-beam exposure system manufactured and marketed by EVC Corporation has a beam diameter of 8 inches and was operated at a beam current of 2 milli amp. The absorption data was collected using a Hitachi U2000 spectrophotometer.
Optical density values at 436 nm as a function of e-beam dosage is plotted in Fig. 6 for e-beam acceleration voltages of 29 kv, 20 kv and 15 kv. In this plot the finite optical density value at zero electron dosage is due to reflection loss of probing light beam at two surfaces of glass plate samples. To obtain an optical density value of 1.0 at 436 nm in HEBS-glass, the required electron dosage is 75µC/cm2, 155µC/cm2, and 270µC/cm>sup>2 using EVC e-beam exposure system at 29 kv, 20 kv, and 15 kv respectively.
The e-beam exposure-induced optical density i.e. net optical density in HEBS-glass is a function of e-beam exposure scheme and write parameters which include e-beam energy (i.e. e-beam acceleration voltage), beam spot size, beam current, addressing grid spacing, and clock rate (i.e. MHz rate). The net optical density is defined herein as the optical density of the e-beam darkened area minus the optical density of the clear (unexposed) area.
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